A series of single, double, and triple Me2biim-bridged dinuclear, trinuclear, and polymeric complexes: syntheses, crystal structures, and luminescent properties

Reaction of ZnCl(2) and Me(2)biim (Me(2)biim = N,N'-dimethyl-2,2-'-biimidazole) in acidic or neutral aqueous solutions gave the noncoordinated ZnCl(4).H(2)Me(2)biim (1) or the double Me(2)biim bridged Zn(2)Cl(4)(mu-Me(2)biim)(2)] (2). Use of CdX(2) (X = Cl, Br, I) instead of ZnCl(2) yielded the single Me(2)biim bridged one-dimensional coordination polymer CdX(2)(mu-Me(2)biim)](n) (X = Cl, 3; Br, 4; I, 5). The stacking of the infinite chains are dominated by C-H...X interactions in 3 and 4 but by I...I interactions in 5, responsible for their different crystal structures. Use of Zn(NO(3))(2) instead of ZnCl(2) produced the novel triple Me(2)biim-bridged Zn(2)(mu-Me(2)biim)(3)(H(2)O)(2)](NO(3))(4).H(2)O (6). The unprecedented hexa-Me(2)bim bridged trinuclear Cd(3)(mu-Me(2)biim)(8)](2)(ClO(4))(12)(H(2)O)(6) (7) was obtained by using Cd(CH(3)CO(2))(2) in the presence of NaClO(4). Compounds 1-7 were characterized by X-ray crystallography and IR. Examination of photophysical properties of 1-7 indicates that the fluorescence emission of Me(2)biim has been effectively enhanced, quenched, or shifted in its metal complexes 1-7.